Stinging nettle leaf extracts are registered in Germany for adjuvant therapy of rheumatic diseases. In a whole blood culture system, the nettle extract IDS 23 (Rheuma-Hek) inhibited lipopolysaccharide stimulated monocyte cytokine expression, indicating an immunomodulating effect. (Antirheumatic Effect of IDS 23, a Stinging Nettle Leaf Extract, on in vitro expression of T helper cytokines). The applicants investigated the immunomodulating effects of betel leaf extracts on phytohemagglutinin (PHA) stimulated peripheral blood mononuclear cells (PBMC) in vitro. Betel leaves has a strong pungent aromatic flavor and widely used as a masticatory. Generally, mature or over mature leaves, which has ceased growing but not yet become brittle are used for chewing. The basic preparation for chewing purposes consists of betel leaf smeared with hydrated lime and catechu to which scrapings of arecanut are added; flavorings such as coconut shavings, clove, cardamon, fennel, powdered liquorice, nutmeg and also tobacco are used according to one's taste. In some places prepared pan is covered with silver or gold leaf As a masticatory, it is credited with many properties: it is aromatic, digestive, stimulant and carminative. Medicinally it is useful in catarrhal and pulmonary affections; it is also used for poultices. The effects of chewing of betel with arecanut and other adjuncts are the excitation of the salivary glands and the irritation of the mucous membrane of the mouth. The red coloration produced is due to a pigment in the arecanut, which manifests itself under the action of alkali in lime and catechu. A mild degree of stimulation is produced, resulting in a sensation of warmth and well being, besides imparting a pleasant odor. The most important factor determining the aromatic value of the leaf is the amount and particularly the nature of the essential oil present. Betel leaves from different regions vary in smell and taste. The most pungent is the Sanchi type, while the most mild and sweet ones are from Madras. The betel leaves contain essential oils, the content of oil varies from 0.7 to 2.6 percent depending upon the varieties of leaves. The oil consists of phenols and terpens. The higher the proportion of phenol oil, the better the quality. An isomer of eugenol named chavibetol (betel phenol; 4-allyl-2-hydroxy-1-methoxy benzene) is considered to be the characteristic constituent of betel oil. It is however, absent in Indian samples. Betel oil of Indian types contain as a predominant phenolic constituent. Oil of betel has been used in the treatment of various respiratory catarrhs, under as a local application either by gargle or by inhalation in diphtheria. It has carminative properties. It exhibits in different action on the central nervous system of mammals; lethal doses produce deep narcosis leading to death within a few hours. The essential oil and extracts of the leaves possess activity against several Gram-positive and Gram-negative bacteria such as Micrococcus pyogenes var. albus and var. aureus, Bacillus subtilis and B. megaterium, Diplococcus pneumoniae, Streptococcus pyogenes, Escherichia coli, Salmonella typhosa, Vibrio comma, Shigella dysenteriae, Proteus vulgaris, Pseudomonas solanacaerum, Sarcina lutea and Erwinia carotovora. The oil is found to be lethal in about 5 minutes to the protozoa Paramaecium caudatum (Wealth of India, Vol.8 pp.84–94). It inhibits the growth of Vibrio cholerae, Salmonella typhosum and Shigella flexneri and Escherichia coli. Steam—distillate of the leaves showed activity against Mycobacterium tuberculosis. 